International Law, Order, and Justice


| Apr 24, 2023

International Law

The Russian invasion of Ukraine that began on February 24, 2022, heralded the emergence of an increasingly realist world order. Russia’s open aggression with flagrant violations of fundamental norms and rules is a clear challenge to the liberal world order that has flourished since the end of the Second World War. In other parts of the world, military coups in Mali, Myanmar, Burkina Faso, and Chad also indicate the realist turn to the world order, where the self-interest of the governing military regime trumps legal commitments to human rights and liberal values.

These challenges to the liberal world order put U.S. foreign policy to the test as we tackle many unanswered questions of international law in the emerging security environment. In February 2023, the Department of Social Sciences at the United States Military Academy, West Point, hosted a Security Seminar to discuss these normative issues, which this post outlines and summarizes in the order of presentation.

Key issues include whether and at which point States may become a party to an armed conflict by providing arms and intelligence, whether and to what extent States are likely to engage in military intervention in a foreign country under the realist world order, and the future role of multilateral pacification in deterring inter-State wars. As the seminar discussion highlighted, Russia’s invasion of Ukraine has brought to the fore many unanswered questions in international law regarding the status of aid-granting States, intervention, and the viability of non-military deterrence methods in an increasingly realist world order.

Military Assistance in International Law: Lessons from Ukraine

February 24, 2022 was a crucial turning point for European security. Russia’s invasion of Ukraine required States not only to reevaluate their own security, but also to analyze the domestic and international legal implications of providing aid to Ukraine in support of its war efforts. Many countries responded to Ukraine’s call for assistance by delivering weapon systems and military equipment. International law, however, remains an underused asset in the effort to undermine Russian aggression.

Several factors influence a State’s stance toward providing military assistance to Ukraine. The provision of military aid is ultimately a political decision, informed by public opinion regarding the war. However, technical expertise is also in the mix, with the military advising politicians on battlefield needs and legal advisers informing them of legal risks associated with aid.

Legal risks are acknowledged because it remains unclear whether military aid can be justified as an exercise of the right of collective self-defense – the right of States to use military force in support of the victim of an armed attack, as provided for in Article 51 of the UN Charter. Under the traditional law of neutrality, neutral States have an obligation to abstain from providing weapons and other military equipment to a belligerent party (§ A breach of neutral obligations, however, could be justified under modern international law as an exercise of the right of collective self-defense when the victim State of an armed attack requests assistance. As the victim of Russia’s aggression, Ukraine has indeed requested that western States provide military assistance, satisfying the requisite conditions for an exercise of collective self-defense by other States.

A separate question is whether military aid makes assisting States a party to the international armed conflict with Russia. The answer to this question carries serious consequences for the United States, along with the many States providing material assistance to Ukraine, because their military assets would become a legitimate military target if they were considered at war with Russia.

It is widely understood that a mere violation of neutrality obligations does not make a State a party to an international armed conflict. It is also axiomatic that Russia’s violations of international law are not relevant to the status of assisting States in the conflict. However, it remains unclear if there is any tipping point where a neutral State becomes a belligerent party due to the degree or nature of military assistance.

Participants at the West Point Security Seminar agreed that providing arms and sharing intelligence does not make a neutral State a party to the conflict. They noted, however, Professor Michael N. Schmitt’s argument that intelligence sharing or other support could, under certain conditions, bring a supporting State into the international armed conflict. That might be the case when the support provided is integral to the conduct of hostile operations or defensive action against the enemy. Although Ukraine’s requests for military assistance are lawful, legal risks associated with State action in response to these requests must be carefully considered.

The war in Ukraine has also provided ample opportunity to test many technologies on the battlefield, such as the integration of cyber and space operations, as well as the production of 3D-printed weapons. Legal risks are increasingly difficult to calculate because there is no precedent regarding military assistance by these technological means. States granting aid must therefore consider the political and legal ramifications of their actions both in the short-term, in responding to Russia’s invasion, and in the longer term. Their actions may set precedents for future conflicts where States might be involved in an armed conflict, with an interest in imposing legal costs for military assistance provided to their adversary.

Humanitarian Intervention under a Realist World Order

The war in Ukraine is the most recent demonstration of incessant struggles for human rights, despite various mechanisms established under the liberal world order that attempt to advance and protect the rights and interests of individuals without any discrimination. The international human rights regime inherently relies upon a liberal world order, sustained both by normative and institutional frameworks that support its end. Since the horrors of the Holocaust during Second World War, nations began to develop deontological values as the basis for intervening in humanitarian crises, but humanitarian motivation may start losing its grip owing to the increasingly realist nature of the world order.

In the most idealistic vision of the liberal world order, States would always be motivated by ideological values such as democracy and individual freedom. However, international society is built on a multi-value system where sovereign States enjoy a prerogative to determine their own governance structure, economic policy, and socio-cultural values. Conflicting values characterized many of the conflicts during the Cold War, with western democracies occasionally justifying military intervention on humanitarian grounds. Despite this historical characterization, the true motivation behind these interventions in the liberal world order has always been realist as well, and more obviously so in today’s security environment.

In his recent publication, Thomas Peak considered how States might respond to genocide in a more realist, post-liberal international order. Regardless of whether the motivations for intervention are realist or liberal, Peak finds that States will continue to intervene to stop genocides out of realpolitik motivations. Great powers, for instance, may be willing to lend their material and political support to generate social capital and to be perceived as good leaders in the eyes of the States they wish to influence.

Participants in the West Point Security Seminar discussed whether the same argument could be applied to collective defense efforts in Ukraine. Third-party States have limited their involvement in the conflict to supplying arms and sharing intelligence. The absence of boots-on-the-ground is a result of their realist considerations taking precedence over moral imperatives for the defense of a liberal world order. A cost-benefit analysis of interference with the Russia-Ukraine war can sufficiently explain why third States continue to respect Russia’s red lines, with cautious and incremental increases in military aid while avoiding direct involvement in the conflict.

Multilateral Pacification – A Possible Deterrent?

Despite the inability of current international legal systems to act as a deterrent against human rights violations and illegal warfare, there are other non-military means at States’ disposal to exact justice for Russian aggression and prevent similar actions in the future. Participants discussed the idea of multilateral pacification – the use of decentralized inter-State cooperation to threaten the use of sanctions to forestall the use of military power in a particular region or against specific States – to determine whether it can mitigate the risk of conflict escalation by minimizing its scope and intensity through targeted sanctions that can hinder or deter a recalcitrant State’s action.

Multilateral pacification can be useful for alliances responding to inter-State aggressions. Multilateral pacification has three main aspects: orientation, function, and membership. Orientation identifies who the alliance desires to pacify, and its function and membership detail which States conduct the pacification and by what means. Multilateral pacification may be a powerful non-military deterrent against inter-State aggressions in an increasingly realist world order, where States increasingly value material self-interest over ideological pursuits.

In practice, however, neither the threat nor the imposition of sanctions deterred Russia from committing an act of aggression and escalating the conflict in Ukraine. Although multilateral pacification has the potential to be a viable tool for preventing the escalation of inter-State wars in the future, the threat and use of sanctions to combat Russian aggression proved ineffective. Reflecting on why multilateral pacification failed in this case will help ensure its effective use in the future.


The outlook of an increasingly realist international order has implications for international law as a political project in managing international relations. Although the emerging realist world order may alter the role that international law plays, it will remain relevant to the future of U.S. national security. The seminar participants discussed policy options that the United States should pursue to strengthen its international standing through its engagement in the Ukraine conflict.

First, the United States and its allies should continue to grant assistance while avoiding direct involvement in an armed conflict. Legal risks associated with military aid should be weighed carefully. International law is the bedrock of the rules-based international order, but the United States and its allies should strive to adapt international law to the reality of modern conflicts where emerging technologies play a significant role.

Second, the United States and its allies should continue to consider intervention as a policy option for humanitarian reasons to promote liberal ideological values. The manner in which States intervene, however, may change from direct deployment of a nation’s soldiers (“boots-on-the-ground”) to more indirect means consistent with the State’s self-interest. The United States should take this change into account in considering how it intervenes in conflicts and the support it can reasonably expect from allies.

Third, the United States and its allies should promote cooperation in imposing sanctions on a particular State (or a threat of sanctions) as a tool to prevent conflict escalation. The United States should take its failure to deter Russia’s invasion of Ukraine as an occasion to expand options for multilateral pacification, not as an indication that this means of preventing conflict is obsolete.

The Department of Social Sciences is grateful to all contributors to this thoughtful panel and hopes that these discussions prompt efforts to further the national security of the United States and its partners in their pursuit of fortitude against aggressive adversaries. The author also thanks Professor Hitoshi Nasu at Lieber Institute, Department of Law, for his support and assistance in completing this report.


Daphne Karahalios is an International Affairs major at the United States Military Academy.


Photo credit: Ministry of Defense of Ukraine